Division of a polyarylene ether solution

ABSTRACT

The invention relates to a process for producing polyarylene ether beads from a polyarylene ether solution, comprising the steps of
     i) dividing the polyarylene ether solution in a division apparatus which is made to vibrate with a frequency of 10 to 1400 Hz to obtain droplets,   ii) transferring the droplets into a precipitation bath to form polyarylene ether beads in the precipitation bath which
       (A) comprises at least one aprotic solvent (component (1)) and at least one protic solvent (component (2)),   (B) has a temperature of 0° C. to T c , where the critical temperature T c  in [° C.] can be determined by the numerical equation T c =(77−c)/0.58 in which c is the concentration of component (1) in the precipitation bath in [% by weight] and   (C) has component (1) in concentrations of 5% by weight to c c , where the critical concentration c c  in [% by weight] can be determined by the numerical equation c c =77−0.58*T in which T is the temperature in the precipitation bath in [° C.], where
 
the percentages by weight are each based on the sum of the percentages by weight of component (1) and of component (2) in the precipitation bath.

The invention relates to a process for producing polyarylene ether beadsfrom a polyarylene ether solution, comprising the steps of

-   i) dividing the polyarylene ether solution in a division apparatus    which is made to vibrate with a frequency of 10 to 1400 Hz to obtain    droplets,-   ii) transferring the droplets into a precipitation bath to form    polyarylene ether beads in the precipitation bath which    -   (A) comprises at least one aprotic solvent (component (1)) and        at least one protic solvent (component (2)),    -   (B) has a temperature of 0° C. to T_(c), where the critical        temperature T_(c) in [° C.] can be determined by the numerical        equation T_(c)=(77−c)/0.58 in which c is the concentration of        component (1) in the precipitation bath in [% by weight] and    -   (C) has component (1) in concentrations of 5% by weight to        c_(c), where the critical concentration c_(c) in [% by weight]        can be determined by the numerical equation c_(c)=77-0.58*T in        which T is the temperature in the precipitation bath in [° C.],        where        the percentages by weight are each based on the sum of the        percentages by weight of component (1) and of component (2) in        the precipitation bath.

The present invention also relates to the polyarylene ether beads fromthe process and to the use thereof for production of polyarylene etherproducts.

In the production of polymers, the polymers are frequently obtained inthe form of polymer solutions. These polymer solutions can arisedirectly in the course of production of the polymers, for example in thepolycondensation of monomers in a solvent (solution polymerization). Inthe case of polycondensation of monomers in the absence of a solvent too(bulk polymerization), the polymers obtained are frequently dissolved ina solvent for further workup.

For conversion of the polymers present in the polymer solution to thepure, solid state, various processes have been described in the priorart. A standard process here is the introduction of the polymer solutioninto a further solvent in which the polymer is insoluble. The furthersolvent in which the polymer is insoluble is generally also referred toas the precipitation bath.

For production of polymer beads, the prior art additionally describesprocesses in which the polymer solution is divided into droplets, fromwhich the polymer beads are subsequently obtained in the precipitationbath. In the processes described in the prior art, the precipitationbath must consist principally of the further solvent in which thepolymer is insoluble. The proportion of the solvent in which the polymeris soluble in the precipitation bath is kept to a minimum. This isnecessary in order to reliably assure the precipitation. In order tominimize the proportion of the solvent in which the polymer is solublein the precipitation bath, generally small volumes of the polymersolution are added dropwise to large volumes of the precipitation bath,or the precipitation bath is exchanged continuously and replaced withfresh precipitation bath.

Processes for producing polymer beads are described, for example, in DE3 644 464 and EP 2 305740. DE 3 644 464 describes a process forproducing polyaryl ether sulfone beads, in which a solution comprising apolyaryl ether sulfone and N-methylpyrrolidone is added dropwise to aprecipitation bath consisting of water. EP 2 305740 also describes aprocess for producing polymer beads, in which pure water is used as theprecipitation bath. The water used as the precipitation bath isexchanged constantly in order to minimize the concentration ofN-methylpyrrolidone and to transport the polymer beads formed onward todownstream process stages.

In the processes described in the prior art for producing polymer beads,there was still room for improvement. The polymer beads obtainable bythe processes described in the prior art tend to agglomerate.Furthermore, the sphericity properties are not always satisfactory. Theprocesses described in the prior art additionally give rise torelatively large amounts of what are called fines. These are polymerbeads which are of very small particle size and which lead to problemsin the further workup or processing of the polymer beads.

The problem addressed by the present invention was that of developing aprocess in which polyarylene ether beads are provided, which do notagglomerate in the precipitation bath and thus can be processed furtherwithout further workup steps.

Conventional division processes and precipitation baths generateparticles having a relatively broad particle size distribution. Theproblem addressed was thus that of providing a process in which smallamounts of fines occur, since fines can block sieves. Nor was too high acoarse fraction to occur, since excessively large polyarylene etherbeads can be extracted only with difficulty. Furthermore, the processwas to run reliably.

The problem addressed by the invention is solved by the processdescribed at the outset.

It has been found that, surprisingly, it is advantageous for productionof polyarylene ether beads to use precipitation baths comprisingrelatively large amounts of at least one aprotic solvent. Contrary tothe prejudice described in the prior art that the precipitation bathused is to comprise a minimum level of solvent in which the polymer hasgood solubility, it has been found that concentrations of at least 5% byweight, preferably at least 8% by weight, more preferably at least 12%by weight, of at least one aprotic solvent (component 1) in theprecipitation bath can prevent or at least reduce the formation of theunwanted fines.

It is suspected that the presence of an aprotic solvent lowers thesurface tension of the precipitation bath, which reduces the formationof fines.

“Fines” in the context of the present invention are understood to meanpolyarylene ether beads having a particle size of ≦1000 μm (lessthan/equal to 1000 μm). The particle size is determined by means ofsieve analysis. The polyarylene ether beads dried at 60° C. areanalyzed.

In one embodiment of the process according to the invention, aprecipitation bath not comprising any aprotic solvent is used at thestart of the process. In this embodiment, the concentration of component(1) at the start is 0% by weight. The inventive concentration of atleast 5% by weight, preferably at least 10% by weight, of component (1)is established in this embodiment by the dropwise addition of thepolymer solution to the precipitation bath. In a further embodiment ofthe process according to the invention, the concentration of component(1) in the precipitation bath even at the start of the process is atleast 5% by weight, preferably at least 8% by weight, more preferably atleast 12% by weight. This embodiment is preferred.

The lower limit of the concentration of component (1) in theprecipitation bath is thus at least 5% by weight, preferably at least 8%by weight and more preferably at least 12% by weight. The percentages byweight are each based on the sum of the percentages by weight ofcomponent (1) and of component (2) in the precipitation bath.

The upper limit of the concentration of component (1) in theprecipitation bath is temperature-dependent. It is also referred to asthe critical concentration c_(c). The unit of c_(c) is [% by weight].

The critical concentration c_(c) in [% by weight] can be determined bythe numerical equationc _(c)=77−0.58*T.T therein is the temperature of the precipitation bath in [° C.]. T thusindicates the actual temperature of the precipitation bath. Proceedingfrom the actual temperature of the precipitation bath, it is possible tocalculate the critical concentration c_(c) in % by weight. Thepercentages by weight are based on the sum of components (1) and (2) inthe precipitation bath.

Within the inventive concentration range from 5% by weight to c_(c), theformation of fines and the agglomeration of the polyarylene ether beadsare very substantially prevented.

Polyarylene ethers are known to the person skilled in the art as apolymer class. In principle, all polyarylene ethers known to thoseskilled in the art and/or preparable by known methods are options.Corresponding methods are explained below.

Preferred polyarylene ethers are formed from units of the generalformula I:

where the symbols t, q, Q, T, Y, Ar and Ar¹ are defined as follows:

-   t, q: each independently 0, 1, 2 or 3,-   Q, T, Y: each independently a chemical bond or group selected from    —O—, —S—, —SO₂—, S═O, C═O, —N═N— and —CR^(a)R^(b)— where R^(a) and    R^(b) are each independently a hydrogen atom or a C₁-C₁₂-alkyl,    C₁-C₁₂-alkoxy or C₆-C₁₈-aryl group, and where at least one of Q, T    and Y is —SO₂— and-   Ar, Ar¹: each independently an arylene group having from 6 to 18    carbon atoms.

If Q, T or Y, among the abovementioned conditions, is a chemical bond,this is understood to mean that the adjacent group to the left and theadjacent group to the right are bonded directly to one another via achemical bond.

Preferably, however, Q, T and Y in formula I are each independentlyselected from —O— and —SO₂—, with the proviso that at least one of thegroup consisting of Q, T and Y is —SO₂—.

If Q, T or Y is —CR^(a)R^(b)—, R^(a) and R^(b) are each independently ahydrogen atom or a C₁-C₁₂-alkyl, C₁-C₁₂-alkoxy or C₆-C₁₈-aryl group.

Preferred C₁-C₁₂-alkyl groups comprise linear and branched, saturatedalkyl groups having from 1 to 12 carbon atoms. Particular mention shouldbe made of the following radicals: C₁-C₆-alkyl radical such as methyl,ethyl, n-propyl, i-propyl, n-butyl, sec-butyl, 2- or 3-methylpentyl andlonger-chain radicals such as unbranched heptyl, octyl, nonyl, decyl,undecyl, lauryl and the singly or multiply branched analogs thereof.

Useful alkyl radicals in the aforementioned usable C₁-C₁₂-alkoxy groupsinclude the alkyl groups having from 1 to 12 carbon atoms defined above.Cycloalkyl radicals usable with preference comprise especiallyC₃-C₁₂-cycloalkyl radicals, for example cyclopropyl, cyclobutyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclopropyl methyl,cyclopropylethyl, cyclopropylpropyl, cyclobutylmethyl, cyclobutylethyl,cyclopentylethyl, -propyl, -butyl, -pentyl, -hexyl, cyclohexylmethyl,-dimethyl, and -trimethyl.

Ar and Ar¹ are each independently a C₆-C₁₈-arylene group. Proceedingfrom the starting materials described below, Ar is preferably derivedfrom an electron-rich aromatic substance subject to easy electrophilicattack, preferably selected from the group consisting of hydroquinone,resorcinol, dihydroxynaphthalene, especially 2,7-dihydroxynaphthalene,and 4,4′-bisphenol. Preferably, Ar¹ is an unsubstituted C₆- orC₁₂-arylene group.

Useful C₆-C₁₈-arylene groups Ar and Ar¹ especially include phenylenegroups such as 1,2-, 1,3- and 1,4-phenylene, naphthylene groups, forexample 1,6-, 1,7-, 2,6- and 2,7-naphthylene, and the arylene groupsderived from anthracene, phenanthrene and naphthacene.

Preferably, Ar and Ar¹ in the preferred embodiment of formula I are eachindependently selected from the group consisting of 1,4-phenylene,1,3-phenylene, naphthylene, especially 2,7-dihydroxynaphthylene, and4,4′-bisphenylene.

Preferred polyarylene ethers are those comprising at least one of thefollowing units Ia to Io as repeat structural units:

In addition to the preferred units Ia to Io, preference is also given tothose units in which one or more 1,4-phenylene units which originatefrom hydroquinone are replaced by 1,3-phenylene units which originatefrom resorcinol or by naphthylene units which originate fromdihydroxynaphthalene.

Particularly preferred units of the general formula I are the units Ia,Ig and Ik. It is also particularly preferred when the polyarylene ethersof component (A) are formed essentially from one kind of units of thegeneral formula I, especially from a unit selected from Ia, Ig and Ik.

In a particularly preferred embodiment, Ar=1,4-phenylene, t=1, q=0, T isa chemical bond and Y═SO₂. Particularly preferred polyarylene ethersulfones (A) formed from the aforementioned repeat unit are referred toas polyphenylene sulfone (PPSU) (formula Ig).

In a further particularly preferred embodiment, Ar=1,4-phenylene, t=1,q=0, T=C(CH₃)₂ and Y═SO₂. Particularly preferred polyarylene ethersulfones (A) formed from the aforementioned repeat unit are referred toas polysulfone (PSU) (formula Ia).

In a further particularly preferred embodiment, Ar=1,4-phenylene, t=1,q=0, T=Y═SO₂. Particularly preferred polyarylene ether sulfones formedfrom the aforementioned repeat unit are referred to as polyether sulfone(PESU) (formula Ik).

Abbreviations such as PPSU, PESU and PSU in the context of the presentinvention conform to DIN EN ISO 1043-1 (Plastics—Symbols and abbreviatedterms—Part 1: Basic polymers and their special characteristics (ISO1043-1:2001); German version EN ISO 1043-1:2002).

The polyarylene ethers preferably have weight-average molecular weightsM_(w) of 10 000 to 150 000 g/mol, especially of 15 000 to 120 000 g/mol,more preferably of 18 000 to 100 000 g/mol, determined by means of gelpermeation chromatography in a dimethylacetamide solvent againstnarrow-distribution polymethylmethacrylate as standard.

In addition, the polyarylene ethers preferably have an apparent meltviscosity at 350° C./1150 s⁻¹ of 150 to 300 Pa s, preferably of 150 to275 Pa s.

The flowability was assessed using the melt viscosity. The meltviscosity was determined by means of a capillary rheometer. The apparentviscosity was determined at 350° C. as a function of the shear rate in acapillary viscometer (Göttfert Rheograph 2003 capillary viscometer) witha circular capillary of length 30 mm, a radius of 0.5 mm, a capillaryinlet angle of 180°, a diameter of the reservoir vessel for the melt of12 mm and with a preheating time of 5 minutes. The values reported arethose determined at 1150 s⁻¹.

Preparation processes which lead to the aforementioned polyaryleneethers are known per se to those skilled in the art and are described,for example, in Herman F. Mark, “Encyclopedia of Polymer Science andTechnology”, third edition, Volume 4, 2003, “Polysulfones” chapter onpages 2 to 8, and in Hans R. Kricheldorf, “Aromatic Polyethers” in:Handbook of Polymer Synthesis, second edition, 2005, on pages 427 to443.

Particular preference is given to the reaction of at least one aromaticcompound having two halogen substituents and at least one aromaticcompound having two functional groups reactive toward the aforementionedhalogen substituents in aprotic polar solvents in the presence ofanhydrous alkali metal carbonate, especially sodium, potassium orcalcium carbonate or mixtures thereof, very particular preference beinggiven to potassium carbonate. A particularly suitable combination isN-methylpyrrolidone as solvent and potassium carbonate as base.

Preferably, the polyarylene ethers have either halogen end groups,especially chlorine end groups, or etherified end groups, especiallyalkyl ether end groups, which are obtainable by reaction of the OH orphenoxide end groups with suitable etherifying agents.

Suitable etherifying agents are, for example, monofunctional alkyl oraryl halide, for example C₁-C₆-alkyl chloride, bromide or iodide,preferably methyl chloride, or benzyl chloride, bromide or iodide, ormixtures thereof. Preferred end groups in the context of the polyaryleneethers of the component are halogen, especially chlorine, alkoxy,especially methoxy, aryloxy, especially phenoxy, or benzyloxy.

A polyarylene ether solution is understood to mean a solution which maycomprise one or more solvents, one or more polyarylene ethers. Thepolyarylene ether solution may additionally comprise materials whichstem from the preparation process. These include impurities, and alsostarting materials. More particularly, the polyarylene ether solutionmay also comprise monomers and salts from the preparation process forthe polyarylene ethers, such as sodium carbonate, potassium carbonate,potassium chloride or sodium chloride. By-products and/or decompositionproducts may also be present in the polyarylene ether solution.

The solvents used for the polyarylene ether solution may be one or moreaprotic solvents. An aprotic solvent is understood to mean a solventwhich does not have a functional group from which one or more hydrogenatoms in the solvent molecule can be eliminated as a proton. Moreparticularly, it is possible to use N-methyl-2-pyrrolidone (NMP),N-ethyl-2-pyrrolidone (NEP), dimethyl sulfoxide, dimethylformamide,sulfolane, 1,2-dichlorobenzene, hexamethylphosphoramide and/or diphenylsulfone or mixtures thereof.

A preferred aprotic solvent is at least one solvent selected from thegroup consisting of N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone(NEP), dimethyl sulfoxide, dimethylformamide, sulfolane and/or diphenylsulfone.

More preferred aprotic solvents are N-methyl-2-pyrrolidone (NMP),N-ethyl-2-pyrrolidone (NEP), dimethyl sulfoxide, sulfolane and/ormixtures of these solvents.

In one embodiment of the present invention, the polyarylene ethersolution comprises the same aprotic solvent as the precipitation bath.The present invention thus also provides a process in which thepolyarylene ether solution and the precipitation bath comprise the sameaprotic solvent.

The polyarylene ether solution preferably has a concentration of 5 to50% by weight of polyarylene ether in aprotic solvent, where thepercentages by weight are based on the sum of the percentages by weightof the polyarylene ether and the aprotic solvent. More particularly, thepolyarylene ether solution may have a concentration of 5 to 40% byweight, preferably of 5 to 35% by weight, more preferably of 5 to 34% byweight, for example of 6 to 30% by weight, of polyarylene ether inaprotic solvent, where the percentages by weight are based on the sum ofthe percentages by weight of the polyarylene ether and the aproticsolvent.

The polyarylene ether solution may have a viscosity of 0.05 to 1.30 Pas, the viscosity being measured in a shear stress-controlled rotaryviscometer, for example having a Couette geometry (DIN 53019-1), at thetemperature at which the division is performed, and at a shear rate of10⁻¹ s⁻¹.

The polyarylene ether solution in the division step may have atemperature of 15 to 250° C., especially of 20 to 120° C., for exampleof 20 to 110° C., the temperature being measurable with the aid of athermometer, for example with a PT100 resistance thermometer, on thedivision apparatus from which the polyarylene ether solution is suppliedto the division apparatus for performance of the division.

In the process for producing polyarylene ether beads from a polyaryleneether solution, a polyarylene ether solution passes through a divisionstep for formation of droplets. It is possible here to use differentkinds of division apparatus. The polymer solution can, for example, besprayed or dropletized.

If the polymer solution is sprayed, the division apparatus used maycomprise one-phase, two-phase or multiphase nozzles. Two-phase ormultiphase nozzles can be employed especially when the polyarylene ethersolution is to be contacted with the precipitation solution actuallybefore it hits the precipitation solution in the precipitation bath.

More particularly, it is possible to select spray nozzles which achievebeads of maximum size. To achieve beads of relatively large size, it ispossible to use spring cone nozzles, i.e. pressure nozzles which areactuated by a spring. To achieve beads of minimum size, it is possibleto use hollow cone nozzles.

If the polyarylene ether solution is divided, one option is to use oneor more die plates as division apparatuses. A die plate is understood tomean a plate of metal, glass or plastic having holes which divide thepolyarylene ether solution.

The diameter of a hole of the die plate may be from 0.1 to 5.0 mm. Moreparticularly, the diameter of one hole of the die plate may be from 0.5to 4.0 mm. Preferably, the diameter of a hole of the die plate is from0.5 to 2.5 mm, especially from 0.5 to 2.0 mm.

It is also possible to use one or more capillaries as the divisionapparatus for dropletization of the polyarylene ether solution. Acapillary is understood to mean an elongate cavity surrounded by aboundary which may be made from metal, glass and/or plastic.

The internal diameter of a capillary may be from 0.1 to 5.0 mm. Moreparticularly, the internal diameter of the capillary may be from 0.5 to4.0 mm. Preferably, the diameter of the capillary may be 0.5 to 2.5 mm,especially from 0.5 to 2.0 mm.

In the division of the polyarylene ether solution to droplets, thedivision apparatus is made to oscillate at a frequency of 10 to 1400 Hz,preferably of 50 to 1000 Hz, especially of 100 to 800 Hz. The divisionapparatus can be made to oscillate longitudinally or transversely. Toproduce longitudinal oscillations, the division apparatus can, forexample, be secured on a membrane which is made to oscillatelongitudinally with the aid of a sound generator using an oscillator.Instead of the sound generator, it is also possible to use apiezoelectric transducer. It is also possible to use oscillators orvibrators to achieve longitudinal or transverse oscillation of thedivision apparatus.

Transverse oscillations are generally produced with vibrators.

In the division of the polyarylene ether solution to droplets, in whichthe division apparatus is made to oscillate, an amplitude of theoscillation of −300 to +300 dBV can be established.

In one embodiment with regard to the division process, the polyaryleneether solution is divided at elevated pressure. In one variant, thepolyarylene ether solution is divided at a gauge pressure of 0.1 to 50bar, especially of 1 to 40 bar, preferably of 1 to 10 bar, morepreferably of 1 to 9 bar. The pressure is measured between the divisionapparatus and the reservoir vessel which comprises the polyarylene ethersolution to be divided, with the aid of a pressure gauge (for example, aspiral spring pressure gauge may be suitable).

The precipitation bath comprises one or more aprotic solvents ascomponent (1). An aprotic solvent is understood to mean a solvent whichdoes not have a functional group from which one or more hydrogen atomsin the solvent molecule can be eliminated as a proton. Moreparticularly, it is possible to use N-methyl-2-pyrrolidone (NMP),N-ethyl-2-pyrrolidone (NEP), dimethyl sulfoxide, dimethylformamide,sulfolane and/or diphenyl sulfone or mixtures thereof.

The precipitation bath furthermore comprises one or more aproticsolvents as component (2).

The precipitation bath may comprise water and/or at least one alcohol ascomponent (2). The water used may be mineralized or demineralized water.The alcohol used may be mono- and/or dihydric alcohols. Preference isgiven to using monohydric alcohols.

The monohydric alcohols used may especially be methanol, ethanol,1-propanol and/or 2-propanol.

The present invention thus also provides a process for producingpolyarylene ether beads from a polyarylene ether solution, comprisingthe steps of

-   iii) dividing the polyarylene ether solution in a division apparatus    which is made to vibrate with a frequency of 10 to 1400 Hz to obtain    droplets,-   iv) transferring the droplets into a precipitation bath to form    polyarylene ether beads in the precipitation bath which    -   (D) comprises at least one aprotic solvent (component (1)) and        at least one protic solvent (component (2)),    -   (E) has a temperature of 0° C. to T_(c), where the critical        temperature T_(c) in [° C.] can be determined by the numerical        equation T_(c)=(77−c)/0.58 in which c is the concentration of        component (1) in the precipitation bath in [% by weight] and    -   (F) has component (1) in concentrations of 5% by weight to        c_(c), where the critical concentration c_(c) in [% by weight]        can be determined by the numerical equation c_(c)=77−0.58*T in        which T is the temperature in the precipitation bath in [° C.],        where        the percentages by weight are each based on the sum of the        percentages by weight of component (1) and of component (2) in        the precipitation bath, and wherein the precipitation bath        comprises water and/or alcohol as component (2).

The precipitation bath preferably comprises a mixture of from 5% byweight to c_(c) of an aprotic solvent, where the percentages by weightare based on the sum of the percentages by weight of the aprotic solvent(component (1)) and of the water and/or alcohol (component (2)) and thissum adds up to 100% by weight.

More particularly, the precipitation bath comprises a mixture of from 8%by weight to cc of an aprotic solvent, where the percentages by weightare based on the sum of the percentages by weight of the aprotic solvent(component (1)) and of the water and/or alcohol (component (2)) and thissum adds up to 100% by weight.

More particularly, the precipitation bath comprises from 5 to 70% byweight of an aprotic solvent as component (1) and from 30 to 95% byweight of water and/or alcohol as component (2), where the sum of thepercentages by weight of components (1) and (2) adds up to 100% byweight. More particularly, the precipitation bath comprises a mixture offrom 8 to 70% by weight of an aprotic solvent as component (1) and from30 to 92% by weight of water and/or alcohol as component (2), where thesum of the percentages by weight of components (1) and (2) adds up to100% by weight.

More preferably, the precipitation bath comprises from 5 to 70% byweight of an aprotic solvent as component (1) and from 30 to 95% byweight of water as component (2), where the sum of the percentages byweight of components (1) and (2) adds up to 100% by weight. Moreparticularly, the precipitation bath comprises a mixture of from 8 to70% by weight of an aprotic solvent as component (1) and from 30 to 92%by weight of water and/or alcohol as component (2), where the sum of thepercentages by weight of components (1) and (2) adds up to 100% byweight.

Most preferably, the precipitation bath comprises from 5 to 70% byweight of N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP),dimethyl sulfoxide and/or sulfolane as component (1) and from 30 to 95%by weight of water as component (2), where the sum of the percentages byweight of components (1) and (2) adds up to 100% by weight. Moreparticularly, the precipitation bath comprises a mixture of from 8 to70% by weight of N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone(NEP), dimethyl sulfoxide and/or sulfolane as component (1) and from 30to 92% by weight of water as component (2), where the sum of thepercentages by weight of components (1) and (2) adds up to 100% byweight.

In a further particularly preferred embodiment, the precipitation bathcomprises 5 to 50% by weight, more preferably 8 to 50% by weight andespecially preferably 12 to 50% by weight of component (1), where thepercentages by weight are each based on the sum of the percentages byweight of component (1) and component (2) in the precipitation bath.

In a further particularly preferred embodiment, the precipitation bathcomprises 5 to 70% by weight, more preferably 8 to 70% by weight andespecially preferably 12 to 70% by weight of component (1), where thepercentages by weight are each based on the sum of the percentages byweight of component (1) and component (2) in the precipitation bath.

As a lower limit, the precipitation bath generally has a temperature ofat least 0° C., preferably of at least 5° C. The upper limit of thetemperature of the precipitation bath depends on the concentration c ofcomponent (1) in the precipitation bath. The upper limit of thetemperature is also referred to as the critical temperature T_(c). Theunit of T_(c) is [° C.].

The critical temperature T_(c) in [° C.] can be determined by thenumerical equationT _(c)=(77−c)/0.58.c therein is the concentration of component (1) in the precipitationbath in [% by weight]. c thus indicates the actual concentration ofcomponent (1) in the precipitation bath. Proceeding from the actualconcentration of component (1) in the precipitation bath, it is possibleto calculate the critical temperature T_(c) in [° C.]. The percentagesby weight are based on the sum of components (1) and (2) in theprecipitation bath.

Within the inventive temperature range from 0° C. to T_(c), preferablyfrom 5° C. to T_(c), the formation of fines and the agglomeration of thepolyarylene ether beads is very substantially prevented.

In one embodiment of the invention, the precipitation bath is agitated.More particularly, the precipitation bath can be stirred. The divisionstep can also be conducted into a flowing precipitation bath.

In one embodiment, the division step takes place in a closedprecipitation bath, the application for individualization being mountedabove the precipitation solution in or on the closed vessel.

In a process for producing polyarylene ether beads, the polyaryleneether solution may cover a distance from the exit point to precipitationbath surface of 0.10 m to 1.20 m. For example, the polyarylene ethersolution may cover a distance from the exit point to precipitation bathsurface of 0.15 m to 1.00 m.

The present invention thus also provides a process for producingpolyarylene ether beads from a polyarylene ether solution whichcomprises an aprotic solvent and has a concentration of 5 to 50% byweight of polyarylene ether in the aprotic solvent, where thepercentages by weight are based on the sum of the percentages by weightof the polyarylene ether and the aprotic solvent, comprising the stepsof

-   i) dividing the polyarylene ether solution in a division apparatus    which is made to vibrate with a frequency of 10 to 1400 Hz to obtain    droplets, wherein the polyarylene ether solution on division has a    temperature of 15 to 250° C.,-   ii) transferring the droplets into a precipitation bath to form    polyarylene ether beads in the precipitation bath which    -   (A) comprises at least one aprotic solvent (component (1)) and        at least one protic solvent (component (2)),    -   (B) has a temperature of 0° C. to T_(c), where the critical        temperature T_(c) in [° C.] can be determined by the numerical        equation T_(c)=(77−c)/0.58 in which c is the concentration of        component (1) in the precipitation bath in [% by weight] and    -   (C) has component (1) in concentrations of 5% to 70% by weight,        where the percentages by weight are each based on the sum of the        percentages by weight of component (1) and of component (2) in        the precipitation bath.

The present invention thus also provides a process for producingpolyarylene ether beads from a polyarylene ether solution whichcomprises an aprotic solvent and has a concentration of 5 to 50% byweight of polyarylene ether in the aprotic solvent, where thepercentages by weight are based on the sum of the percentages by weightof the polyarylene ether and the aprotic solvent, comprising the stepsof

-   i) dividing the polyarylene ether solution in a division apparatus    which is made to vibrate with a frequency of 10 to 1400 Hz to obtain    droplets, wherein the polyarylene ether solution on division has a    temperature of 15 to 250° C.,-   ii) transferring the droplets into a precipitation bath to form    polyarylene ether beads in the precipitation bath which    -   (A) comprises at least one aprotic solvent (component (1)) and        at least one protic solvent (component (2)),    -   (B) has a temperature of 0° C. to T_(c), where the critical        temperature T_(c) in [° C.] can be determined by the numerical        equation T_(c)=(77−c)/0.58 in which c is the concentration of        component (1) in the precipitation bath in [% by weight] and    -   (C) has component (1) in concentrations of 5% to 70% by weight,        where        the percentages by weight are each based on the sum of the        percentages by weight of component (1) and of component (2) in        the precipitation bath and wherein the precipitation bath        comprises water and/or alcohol as component (2) and the aprotic        solvent is selected from the group consisting of        N-methylpyrrolidone, N-ethylpyrrolidone, dimethyl sulfoxide,        dimethylformamide, sulfolane, diphenyl sulfone,        1,2-dichlorobenzene, hexamethylphosphoramide and mixtures        thereof.

In addition, the invention relates to beads from the process forproduction of polyarylene ether beads. After the division step, thebeads are present in the precipitation bath solution. The beads can beseparated from the further constituents present in the precipitationbath by suitable means. For example, the beads can be removed bysieving.

In general, the beads have a residence time in the precipitationsolution of 1 min to 2 days.

The application also relates to the use of beads for production ofpolyarylene ether products. Polyarylene ether products are understood tomean products which have been subjected to extraction, drying and/or ashaping process. For instance, the application also relates to productsfrom the process, which, after workup such as extraction and drying, areconverted to a saleable form such as pellets, powders, granules, chips,grains or fibers.

EXAMPLES

Experiments 1 to 25 were conducted with various illustrative polyaryleneether solutions, all of which are described in table 1.

The solutions used were adjusted to the respective concentrations.

TABLE 1 Description of the polyaryl ether solutions. Solution Structureof the Concentration in the number Solvent polyaryl ether solvent [% bywt.] 1 NMP Formula I 21 2 NMP Formula I 17 3 NMP Formula II 16 4 NMPFormula II 18

The viscosity number determination was conducted to ISO1628 from a 0.01g/ml solution in phenol/1,2-dichlorobenzene (1:1) at 25° C.

The polyaryl ether solution, the concentration of which has beenadjusted, was run from a reservoir vessel at a constant delivery ratethrough a capillary for division to form droplets. The experiments wereconducted with a capillary as the division apparatus, and it waspossible to cause the capillary to oscillate by the use of a vibrator.The capillary diameter, the fall distance from exit from the capillaryto the precipitation bath surface and the oscillation parameters werevaried, as specified in the tables below.

After the division, the droplet of the respective polymer solution fellinto a precipitation bath. The temperature and composition of theprecipitation bath were kept constant during an experiment.

The beads formed in the operation were removed with the aid of a sieve.To study the product, the precipitated polymer was extracted with waterat a temperature of 95° C. for 20 hours. For this purpose, the beadswere introduced into a vessel through which 160 l of water per hourflowed. Subsequently, the beads were dried at 150° C. under reducedpressure for two days.

Various analyses were conducted.

A sieve analysis was conducted with the extracted and dried polyarylether sulfone beads. The amount of the product was 40 to 75 g in eachcase. The beads were weighed and then introduced into a vibratingmachine. The vibrating machine consisted of several screens, with thecoarser screen arranged higher in each case. The mesh sizes of thescreens were: 3.15 mm, 2.5 mm, 2 mm, 1.6 mm, 1.25 mm, 1.0 mm, 0.63 mm,0.5 mm, 0.4 mm, 0.2 mm. The vibrating machine ran for 15 minutes.Subsequently, the residues on the individual screens were weighed andthe weights were added up to determine a particle size distribution.

After extraction for 7 hours, a sample was taken from the extractionvessel and the NMP content in the particles was determined by gaschromatography (GC) analysis.

Examples 1 to 9: Influence of Oscillation

In examples 1 to 7, solution 1 was used. The temperature of the polyarylether solution in the division apparatus was 70° C. The precipitationbath consisted of a water/NMP mixture (80% by weight of water/20% byweight of NMP). The temperature of the precipitation bath was keptconstant at 35° C. The precipitation height was likewise kept constantat 80 cm.

NMP content Particle size: Particle size: in particles Vibration of thecapillary Capillary Through- Fines fraction Coarse fraction after7-stage Frequency Amplitude diameter put (particles <1 mm) (particles >2mm) extraction Ex. Use [Hz] [dbV] [mm] [g/h] % by wt. % by wt. % by wt.1 no — — 1 1980 3.2 7.6 0.55 2 yes 150 50 1 1974 1.9 0.7 0.35 3 no — — 1900 0.5 3 n.d. 4 no — — 1 1400 0.6 58.6 n.d. 5 yes 150 50 1 1068 2.1 0.5n.d. (n.d.: not determined)

Examples 1 and 2 show an improvement in the extractability of the beadsby the use of a vibrating division apparatus (the NMP content wasreduced by 36% in the polyaryl ether particles).

NMP content Particle size: Particle size: in particles Vibration of thecapillary Capillary Through- Fines fraction Coarse fraction after7-stage Frequency Amplitude diameter put (particles <0.63 mm)(particles >1.6 mm) extraction Ex. Use [Hz] [dbV] [mm] [g/h] % by wt. %by wt. % by wt. 6 no — — 0.7 1800 0.2 89 0.58 7 yes 187 50 0.7 2020 4.30.3 0.25

Examples 6 and 7 show an improvement in the extractability of the beadsby the use of a vibrating division apparatus (the NMP content wasreduced by 57% in the polyaryl ether particles).

In examples 8 to 10, solution 2 was used. The temperature of thepolyaryl ether solution at the capillary was 70° C. The precipitationbath consisted of a water/NMP mixture (80% by weight of water/20% byweight of NMP). The temperature of the precipitation bath was keptconstant at 35° C. The precipitation height was likewise kept constantat 80 cm.

NMP content Particle size: Particle size: in particles Vibration of thecapillary Capillary Through- Fines fraction Coarse fraction after7-stage Frequency Amplitude diameter put (particles <0.63 mm)(particles >1.6 mm) extraction Ex. Use [Hz] [dbV] [mm] [g/h] % by wt. %by wt. % by wt. 8 no — — 0.7 1400 0.4 57 0.0085 9 yes 215 100 0.7 1488 019 0.0045

In examples 8 and 9, an improvement in the extractability of the beadswas obtained by the production of a narrower particle size distribution(the NMP content was reduced by 47% in the polyaryl ether particles).

Examples 10 to 25: Influence of Precipitation Bath Composition

In examples 10 to 17, solution 3 was used. The temperature of thepolyaryl ether solution at the capillary was 70° C. The capillarydiameter was 0.7 mm. The precipitation height was kept constant at 80cm. The throughput was likewise kept constant at 2064 g/h.

Experiments were conducted at different temperatures and composition, asspecified in the tables.

The NMP content in the precipitation bath was increased from 20% byweight until the beads present in the precipitation bath agglomerated.Agglomeration of the beads is disadvantageous since such beads cannot beprocessed any further.

Variation of the NMP content of the precipitation bath at precipitationbath temperature 35° C.:

Precipitation bath Vibration of the capillary NMP Frequency Amplitude Tcontent Precipitation Ex. Use [Hz] [dbV] [° C.] [% by wt.]characteristics 10 yes 161 100 35 20 Individual beads 11 yes 161 100 3540 Individual beads 12 yes 161 100 35 50 Individual beads 13 yes 161 10035 58 Beads which agglomerate in the precipitation bath

Variation of the NMP content of the precipitation bath at precipitationbath temperature 50° C.:

Precipitation bath Vibration of the capillary NMP Frequency Amplitude Tcontent Precipitation Ex. Use [Hz] [dbV] [° C.] [% by wt.]characteristics 14 yes 161 100 50 20 Individual beads 15 yes 161 100 5030 Individual beads 16 yes 161 100 50 40 Individual beads 17 yes 161 10050 50 Beads which agglomerate in the precipitation bath

In examples 18 to 25, solution 4 was used. The temperature of thepolyaryl ether solution at the capillary was 70° C. The capillarydiameter was 0.7 mm. The precipitation height was kept constant at 80cm. The throughput was likewise kept constant at 3780 g/h.

The precipitation bath temperature and precipitation bath compositionwere kept constant within an experiment. Experiments were conducted atdifferent temperatures and composition, as specified in the tablesbelow.

The NMP content in the precipitation bath was increased from 20% byweight until the beads present in the precipitation bath agglomerated.Agglomeration of the beads is disadvantageous since such beads cannot beprocessed any further.

Variation of the NMP content of the precipitation bath at precipitationbath temperature 35° C.:

Precipitation bath Vibration of the capillary NMP Frequency Amplitude Tcontent Precipitation Ex. Use [Hz] [dbV] [° C.] [% by wt.]characteristics 18 yes 206 100 35 20 Individual beads 19 yes 206 100 3540 Individual beads 20 yes 206 100 35 50 Individual beads 21 yes 206 10035 58 Beads which agglomerate in the precipitation bath

Variation of the NMP content of the precipitation bath at precipitationbath temperature 50° C.:

Precipitation bath Vibration of the capillary NMP Frequency Amplitude Tcontent Precipitation Ex. Use [Hz] [dbV] [° C.] [% by wt.]characteristics 22 yes 161 100 50 20 Individual beads 23 yes 161 100 5030 Individual beads 24 yes 161 100 50 40 Individual beads 25 yes 161 10050 50 Beads which agglomerate in the precipitation bath

Examples 26 to 31 show the influence of the concentration of aproticsolvent in the precipitation bath on the formation of fines. “Fines” areunderstood here to mean polyarylene ether beads having a particle sizeof ≦1000 μm.

For this purpose, a solution 5 of polyarylene ether in sulfolane or NMPwas prepared. The polyarylene ether used was Ultrason® E2020 from BASFSE. The concentration of the polyarylene ether in sulfolane was 16.0% byweight the concentration of the polyarylene ether in NMP was 18.0% byweight.

The polyarylene ether was precipitated by means of dropletization andthen extracted.

For the dropletization, solution 5 was introduced into the reservoirvessel and adjusted to the desired temperature. By means of a gear pump,solution 5 was dropletized through a capillary. The precipitation waseffected in a precipitation bath with an overflow to an agitated screenwhich removed the beads. The precipitation bath solution was collectedin a buffer vessel and then sent back to the precipitation bath.

The concentration of NMP or sulfolane in the precipitation bath wasmonitored by means of refractive index and balanced by addition ofdemineralized water. After dropletization had ended, the beads/lenseswere filtered off with suction, washed with demineralized water and thenextracted.

The conditions during the dropletization are specified in the followingtable:

Conc. solv. in Precip- Temp. of Conc. the pre- itation solution 5 insolu- cipita- bath on drop- Fall tion 5 tion bath temp. letizationheight Exp. Solvent [% by wt.] [%] [° C.] [° C.] [cm] 26 NMP 18.0 40 4040 30 27 NMP 18.0 <1 40 40 30 28 sulfolane 16.0 <1 40 80 60 29 sulfolane16.0 40 40 80 60

The conditions in the extraction with water were as follows:

The extracted moist beads/lenses were dried in a drying cabinet at 60°C. and then the distribution was determined by means of manual screeningin a screening tower. The results are reported in the table whichfollows.

Particle size [μm] 28 29 26 27 3150 99.16 100.0 100.0 99.80 2800 97.4999.89 99.78 99.01 2500 92.48 99.21 98.49 97.43 2000 27.69 30.51 54.9630.56 1600 8.88 2.94 8.62 5.84 1250 5.33 0.45 3.45 2.67 1000 4.28 0.231.08 1.68  650 3.87 0.45 0.22 0.69 Sum ≦1000 = 8.15 0.68 1.3 2.37 fines

Examples 30 and 31 were conducted analogously to examples 26 to 29. Thefall height and the temperature were altered; the concentration of theprecipitation bath was varied. The results are reported in the tablewhich follows.

Precipitation bath PES soln. Fall Fines frac- Conc. NMP Temp. SC Temp.height tion <1 mm Exp. [%] [° C.] [%] [° C.] [cm] [%] 30 20 35 23 65 900.37 31 1 35 23 65 90 0.93

Examples 26 to 31 show that, within the inventive concentration range ofaprotic solvent in the precipitation bath, polyarylene ether beadshaving a distinctly smaller fines fraction are obtained.

The invention claimed is:
 1. A process for producing polyarylene etherbeads, the process comprising: i) dividing a polyarylene ether solutionin a division apparatus vibrating at a frequency of 10 to 1400 Hz toobtain droplets; and ii) transferring the droplets into a precipitationbath to form polyarylene ether beads, wherein: the precipitation bathsatisfies the following conditions (A) the precipitation bath comprisesat least one aprotic solvent (component (1)) and at least one proticsolvent (component (2)), (B) the precipitation bath has a temperature of0° C. to T_(c), where the critical temperature T_(c) in [° C.] isdetermined by the numerical equation T_(c)=(77−c)/0.58 in which c is theconcentration of the component (1) in the precipitation bath in [% byweight], and (C) the precipitation bath has the component (1) inconcentrations of 5% by weight to c_(c), where the criticalconcentration c_(c) in [% by weight] is determined by the numericalequation c_(c)=77−0.58*T in which T is the temperature in theprecipitation bath in [° C.]; percentages by weight are each based on asum of the percentages by weight of the component (1) and of thecomponent (2) in the precipitation bath; the precipitation bathcomprises water, alcohol, or both, as the component (2); the polyaryleneether solution has a concentration of 5 to 50% by weight of polyaryleneether in the at least one aprotic solvent, where percentages by weightare based on a sum of the percentages by weight of the polyarylene etherand the at least one aprotic solvent; the polyarylene ether solution ondivision has a temperature of 15 to 250° C.; the aprotic solvent isselected from the group consisting of N-methylpyrrolidone,M-ethylpyrrolidone, dimethyl sulfoxide, dimethylformamide, sulfolane,diphenyl sulfone, 1,2-dichlorobenzene, hexamethylphosphoramide andmixtures thereof; and wherein, in the polyarylene ether beadsprecipitated from the precipitation bath in (ii), a content of particleshaving a particle size of less than or equal to 1000 μm is 2.1% byweight or less.
 2. The process according to claim 1, wherein theprecipitation bath is agitated.
 3. The process according to claim 1,wherein the polyarylene ether solution on division has a temperature of20 to 120° C.
 4. The process according to claim 1, wherein thepolyarylene ether solution after leaving the division apparatus covers afull distance from the exit point to the precipitation bath surface of0.10 m to 1.20 m.
 5. The process according to claim 1, wherein thedivision apparatus comprises capillaries, die plates, or both.
 6. Theprocess according to claim 5, wherein the division apparatus comprises aperforated plate comprising at least one capillary, hole, or both havinga diameter of 0.1 to 5.0 mm.
 7. The process according to claim 1,wherein the polyarylene ether solution and the precipitation bathcomprise the same aprotic solvent.
 8. The process according to claim 1,wherein the precipitation bath comprises 12 to 50% by weight, of thecomponent (1), where the percentages by weight are each based on the sumof the percentages by weight of component (1) and component (2) in theprecipitation bath.
 9. The process according to claim 1, furthercomprising stirring the precipitation bath when transferring thedroplets into the precipitation bath.
 10. The process of claim 1,wherein, in the polyarylene ether beads precipitated from theprecipitation bath in (ii), the content of particles having a particlesize of less than or equal to 1000 μm is 1.3% by weight or less.
 11. Theprocess according to claim 1, wherein the polyarylene ether beads areindividual beads which are not agglomerated.